Winding through the meadow for nearly a mile, the trail climbs a short way above the now-dry river bed, then intersects with the Harvey Moore Trail. Here I saw lots of snake tracks on the sandy trail.

But instead of taking that long Harvey Moore trail to the right (east), take the unmarked trail to the left (northwest) for another 0.6 mile. You cross the river bed, but it’s noticeably dry throughout this part of the valley.

You head up just a bit until you go back into the mountain meadow again. On the way up, look for scarlet buglers, pink California roses, yellow wallflowers, and lots of blue elderberry shrubs whose white flowers bunch all over the bush in showy clusters.

After that 0.6 mile, the trail intersects with the Upper Green Valley Fire Road, where you turn left (southwest) for another 0.4 mile to continue this loop.

The next intersection offers a 0.3-mile connector trail to the Cold Stream Trail, where you started, or you can continue straight ahead on the fire road for another 0.4 mile to reach the visitors center again.

I took the connector trail to the Cold Stream Trail for good reason. That last 0.4 mile of the Cold Stream Trail back to your parking area has one of the grandest oak trees in the park: Grandfather Oak.

You’ll see it nearly straight ahead where the connector trail meets up again with Cold Stream Trail, where you turn left (south). A short way off the trail takes you right up to the great old oak, marked No. 13, the last marker on the Cold Stream Trail’s Kumeyaay Nature Trail that you now backtrack on to return to the parking area.

“Many stories have been told under the shade of this tree,” says the accompanying brochure for the Kumeyaay Nature Trail. “My grandparents told me they used to play under its branches and that their grandparents did, too.”

That enormous oak is surely more than 200 years old. Look for the ax blade stuck in the base of its trunk for probably the last 100 years.

If you pick up the nature trail pamphlet at the visitors center before you head out, you can follow the numbered markers to learn about plants and trees used by the Kumeyaay who lived here for generations.